The path an oxygen molecule takes to get from the abiotic environment into a cell :
From the nose it follows the respiratory track (pharynx, trachea, bronchi) to the lungs where in the alveoli it passively diffuses into the blood enters the red blood cells and gets attached to an iron atom in haemoglobin.
It is then transported to the body where it gets released and passively diffuses into a cell to be used in cellular respiration to accept electrons that originated in fuel molecules.
